PESHAWAR, PAKISTAN — Up to 250 people, including at least 45 soldiers, have been killed in fierce fighting in northwestern Pakistan over the past four days, with Pakistani military jets bombing suspected insurgent hide-outs amid tough resistance, officials and residents said Tuesday.

The military said that at least 150 insurgents had been killed in the battles in North Waziristan, a remote tribal region that al-Qaida and Taliban fighters have used as a base for operations.

The most intense clashes have come in the town of Mir Ali, where the military has deployed heavy artillery, helicopter gunships and fighter jets to try to oust insurgents who have been waging an aggressive campaign against the Pakistani army.

The use of fighter jets is unusual, but government officials said it was necessary given the strength of the firepower they were facing from the insurgents.

"The resistance from local Taliban is tougher than what the government usually expects," conceded a tribal affairs official in Peshawar, the capital of North-West Frontier province. "Such tough resistance also gives credence to speculation that al-Qaida-trained foreign fighters might be backing these local Taliban."

Heavy civilian toll

The fighting, which began late Saturday with an insurgent strike on a military convoy, has taken a heavy toll on civilians. There were reports Tuesday of large numbers of casualties among residents caught in the crossfire. Civilians in some villagers used mosque loudspeakers to appeal to both sides not to target homes or shopping areas.

Meanwhile, a full-scale exodus was under way for those who were able to leave.

Mohammad Zarin, 33, made it from Mir Ali to the nearby town of Bannu on Tuesday with his mother, wife, three children, sister-in-law, three nephews and two nieces.

"It was a hard decision to leave our home in Mir Ali. But life is more precious than material things," Zarin said by phone. "We decided to leave our home for the sake of our children." For others, it was too late.

"I have seen people digging graves for the dead bodies," said Malik Mumtaz, a tribal elder from North Waziristan. "Others are busy rushing their injured to the nearby hospitals."

Military officials conceded the heavy fighting may have resulted in civilian casualties, but they wouldn't give specifics.

Mumtaz said two Pakistani army jets had bombed the village of Aipi at around 4:30 p.m. Tuesday, killing about 50 tribesmen. That account was impossible to verify.

White House weighs in

Rising militancy in the tribal areas has been a major concern for the United States. Tuesday's fighting came as the White House released a report that again pointed to Pakistan's tribal belt as an operational headquarters for al-Qaida and other extremist groups.

The problem was only exacerbated, the White House has said, by a 2006 peace deal in North Waziristan that required the Pakistani military to pull back to its barracks. The deal fell apart this summer, but many critics contend that Pakistan is now suffering the consequences of a policy that allowed extremist groups to rebuild.

"I have said repeatedly that the peace agreement with the tribals in Pakistan failed Pakistan and it failed us," Frances Fragos Townsend, White House homeland security adviser, said in a conference call with reporters. "And obviously, that's one of the fundamental things that al-Qaida took advantage of to re-establish a safe haven in the tribal areas."

Townsend refrained from directly criticizing embattled Pakistani President Pervez Musharraf. Instead, she emphasized the U.S. commitment to working with his government.

Musharraf's cooperation with the United States on counterterrorism efforts has not been popular in Pakistan.

"The military operations are being conducted for the sole purpose of appeasing the United States at the expense of innocent tribesmen who have nothing to do with al-Qaida and the Taliban," said Mumtaz, the tribal elder.